A new look into the reaction between ergosterol and singlet oxygen in vitro

Abstract

The reaction of ergosterol (ERGO) with singlet oxygen in vitro was studied by using different combinations of the photosensitizers (i.e. rose Bengal and eosine) and solvents (i.e. pyridine, ethanol and methyl tert-butyl ether) and all the products obtained were isolated and fully characterized (mp, Rf, UV, 1H-NMR, 13C-NMR, EI-MS, ESI-MS and HR-MS). In pyridine. together with the expected (22E)-5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol, EEP, the keto derivative (22E)-3beta-hydroxyergosta-5,8(9),22-trien-7-one. KE, was obtained. In ethanol the expected EEP was obtained together with (22E)-5alpha,8alpha-epidioxyergosta-6,9,22-trien-3beta-ol, EEP9(11), and (22E)-ergosta-6,9,22-triene-3beta,5alpha,8alpha-triol, DHOE, as main products and (22E)-ergosta-5,7,9,22-tetraen-3beta-ol, DHE, in trace amounts In methyl tert-butyl ether, a complex mixture of EEP, KE, DHOE, EEP9(11), DHE, together with (22E)-7alpha-hydroperoxyergosta-5.8(9),22-trien-3beta-ol, EHP, and (22E)-ergosta-5,8(9),22-triene-3beta, 7alpha-diol, EH, was obtained. The minor products were characterized and showed strong dependence on the reaction medium. The regioselective and stereoselective character of the singlet oxygen attack on the ERGO diene moiety is discussed in terms of ERGO HOMO's properties.

Six novel steroids from culture of basidiomycete Polyporus ellisii

“…Comparison of the physicochemical properties with the reported data allowed to identify compounds 7-10, isolated from the same fungus, as 3β,15α-dihydroxy-(22E,24R)-ergosta-5,8(14),22-trien-7-one (7) 4 , 3β,15β-dihydroxy-(22E,24 R)-ergosta -5,8(14),22-trien-7-one (8) 4 , (22E,24R)-ergosta-6,9, 22-trien-3β,5α,8α-triol (9) 5 , (22E,24R)-ergosta-4,6,8(14),22-tetraen-3,15-dione (gymnasterone, 10) 6 , respectively.…”

“…The stereochemistry of H-3 was determined to be α-oriented due to its downfield shifted broad multiplet at δ H 3.96 (W 1/2 = 20.0 Hz) 10,11 . The stereochemistry of the side chain of 2 was established by the comparison with the known compounds (7-10) [4][5][6] and literature data of similar compounds. 7,8 Thus, 2 was assigned as 5β,6β-epoxy-3β,7α,9α-trihydroxy-(22E,24R)-ergosta-8(14),22-dien-15-one.…”

“…The ROESY (in DMSO-d 6 ) correlations between 9-OH and H-3 indicated the existence of 3β-OH. The stereochemistry of the side chain was established by the comparison with the known compounds (7-10) [4][5][6] and literature data of similar compounds 7,8 . Thus, 1 was elucidated as 3β,9α,15α-trihydroxy-(22E,24R)-10(5→4)-abeo-ergosta-6,8(14),22-trien-5-one.…”

“…In addition, three new multioxygenbearing ergosterols, namely 5β,6β-epoxy-3β,7α,9α-trihydroxy-(22E,24R)-ergosta-8(14),22-dien-15-one (2), 5β,6β-epoxy-3β,7α-dihydroxy-(22E,24R)-ergosta-8(14),22-dien-15-one (3), 5α,6α-epoxy-3β,9α,15α-trihydroxy-(22E,24R)-ergosta-8(14),22-dien-7-one (4), and two derivatives of (22E,24R)-ergosta- 4,6,8(14),22-tetraen-3-one, namely 15α-acetoxy-(22E, 24R)-ergosta- 4,6,8(14),22-tetraen-3-one (5), 15β-methoxy-(22 E,24R)-ergosta- 4,6,8(14),22-tetraen-3-one (6), were obtained. Four known ergosterols, 3β,15α-dihydroxy-(22E,24R)-ergosta-5,8(14),22-trien-7-one (7) 4 , 3β,15β-dihydroxy-(22E,24R)-ergosta-5,8(14),22-trien-7-one (8) 4 , (22E,24R)-ergosta-6,9,22-trien-3β,5α,8α-triol (9) 5 , (22E,24R)-ergosta- 4,6,8(14),22-tetraen-3,15-dione (gymnasterone, 10) 6 were also isolated from the species. New compounds were evaluated for cytotoxicity against five human cancer cell lines.…”

Steroidal and Triterpenoidal Fungal Metabolites as Ligands of Liver X Receptors

“…5 was characterized by mass and 2D NMR spectral analysis. While the 7R analog was prepared in 6ϳ9% yield from ergosterol (1) by in vitro singlet oxygen reaction [20] this is first report of this compound from nature. This broth also produced small amounts of …”